Method and Apparatus for Fluid Pumping

ABSTRACT

A fluid balanced hydraulic pump has a support tower that can be mounted over a well. At least one cylinder assembly is pivotally mounted within the support tower. A prime mover provides hydraulic fluid to the at least one cylinder assembly through a wedge spool control valve that provides precise speed control with minimal maintenance requirements. Stroke speed can be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.

STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

NONE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a hydraulic pumping unit. More particularly, the present invention pertains to a hydraulic pumping unit that provides precise rod speed control with minimal maintenance requirements.

2. Brief Description of the Prior Art

Liquid-producing subterranean reservoirs all have some level of energy or potential, frequently referred to as “reservoir pressure” that will force fluid (liquid, gas or a mixture) to areas of lower energy or potential. If a well penetrates such a reservoir, and if the pressure inside such a well is decreased below the reservoir pressure, fluids will feed into the well from said formation. However, depending on the depth of the reservoir and density of the fluid(s), the reservoir may not have sufficient reservoir pressure to push the fluid to the surface. The deeper the well, or the heavier the fluid(s), the higher the reservoir potential that is required to push such fluid(s) to the surface.

Many hydrocarbon producing reservoirs have sufficient potential to naturally produce oil and gas (which are relatively light, compared to water) during the early stages of production. However, as a well continues to produce, reservoir pressure will often decrease as a reservoir depletes. Further, in many reservoirs, formation water will eventually encroach into the wellbore, causing the lifting requirements to be much greater than for just oil and/or gas. Either or both of these conditions can cause production from a well to decline, or possibly even cease entirely.

As a result of the foregoing, artificial means are often used to continue or increase the flow of liquids (such as crude oil, water or a mix of oil and water) from subterranean reservoir(s) to the earth's surface. As noted above, such “artificial lift” can be required when insufficient reservoir pressure exists to lift produced fluids to the surface in a well. Artificial lift can also be employed in flowing wells to increase the flow rate above what would occur naturally.

Although numerous different means of artificial lift exist, one common type involves the use of a mechanical device known as a “rod pump” inside a well. Such rod pumps, which are well known to those having skill in the art, are typically elongate cylinders with both fixed and moveable elements. Such rod pumps are designed to be installed down-hole inside of wells, at or near the depth of the reservoir(s) from which production is obtained, to gather fluids from below and lift said fluids within the wells to the surface. In many instances, such down-hole pumps have a barrel equipped with two ball check valves: a stationary valve near the bottom of said barrel, and a traveling valve that moves up and down. As reservoir fluids enter a well from a down-hole reservoir(s), the down-hole pump lifts such fluids from said subterranean reservoir(s) to the surface within said well.

Rod pump systems generally comprise a reciprocating down-hole pump situated within a well at or near a subterranean reservoir, an above-ground drive mechanism at the earth's surface, and a length of elongate cylindrical rods (frequently referred to as “sucker rods”) connecting said down-hole pump to said surface drive mechanism in said well. In many conventional installations, said surface drive mechanism comprises a pump-jack (also sometimes referred to as a pumping unit, horsehead pump, rocking horse, beam pump, or jack pump) that converts rotary motion (from an electric motor or internal combustion engine, for example) to a reciprocating vertical motion in order to drive a reciprocating down-hole pump via the sucker rods. Such pump-jacks generally exhibit a characteristic nodding motion.

Although very common, conventional pump-jacks and other types of surface drive mechanisms suffer from a number of significant shortcomings. Said surface drive mechanisms can be large, cumbersome and difficult to install in many instances. Further, such conventional surface drive mechanisms are typically complicated, and expensive to manufacture, operate and maintain.

Thus, there is a need for a pumping apparatus having a surface drive mechanism that is relatively inexpensive, durable and simple to operate. The hydraulic pumping apparatus should provide precise rod speed control with minimal maintenance requirements, while permitting stroke speed to be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.

SUMMARY OF THE PRESENT INVENTION

The present invention comprises a hydraulic pumping apparatus having an improved surface drive mechanism. By way of illustration and not limitation, the present invention is described herein as a hydraulic pumping apparatus installed on a well for pumping fluids from subterranean formations. However, it is to be observed that the hydraulic pumping apparatus of the present invention, and components thereof, can be used in many different applications involving the pumping of fluid(s) beyond the particular embodiment described herein.

In a preferred embodiment, the hydraulic pumping apparatus of the present invention comprises an elongate tower assembly that can be mounted at the surface of a well. Said tower assembly provides a rigid frame for supporting at least one hydraulic cylinder assembly that is oriented substantially parallel to said tower assembly. In the preferred embodiment, said elongate tower assembly (and the at least one hydraulic cylinder assembly supported therein) are mounted in substantially axial alignment over said well at the earth's surface. Said at least one hydraulic cylinder assembly is connected to a bridle assembly attached to a polished rod; said polished rod is, in turn, connected to a length of interconnected sucker rods that extend into said well. A down-hole pump mechanism is mounted near the bottom of said well and is attached to the distal end of said sucker rods.

Said at least one hydraulic cylinder assembly can be beneficially mounted to said elongate tower assembly using a self-centering pivot mounting assembly. Said self-centering pivot mounting assembly ensures that said at least one hydraulic cylinder assembly finds the center of gravity, thereby preventing unwanted side loading on said at least one cylinder assembly.

A prime mover assembly provides hydraulic fluid used to actuate said at least one hydraulic cylinder assembly. Hoses or other conduits connect said prime mover to a wedge spool valve disposed between said prime mover and said at least one cylinder assembly. Said wedge spool valve can be used to control the stroking of said at least one hydraulic cylinder assembly and, in turn, the reciprocation of said sucker rods in and out of said well.

The hydraulic pumping apparatus of the present invention is inexpensive, durable and simple to operate. Further, the hydraulic pumping apparatus of the present invention has a small footprint and can be directly mounted to wells having shallow to medium depths or, alternatively, skid supported for wells extending to deeper depths. The hydraulic pumping apparatus of the present invention further provides for precise rod speed control with minimal maintenance requirements. Stroke speed can be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed. Further, dimensions, materials and part names are provided for illustration purposes only and not limitation.

FIG. 1 depicts a front perspective view of the support tower of the hydraulic pumping apparatus of the present invention.

FIG. 2 depicts a front perspective view of the support tower of the hydraulic pumping apparatus of the present invention including an optional support base.

FIG. 3 depicts a front view of the hydraulic pumping apparatus of the present invention installed on a well.

FIG. 4 depicts a side view of the support tower of the hydraulic pumping apparatus of the present invention installed on a well.

FIG. 5 depicts a rear view of the hydraulic pumping apparatus of the present invention installed on a well.

FIG. 6 depicts a side sectional view of the wedge spool control valve of the present invention.

FIG. 7 depicts a side view of the distal end of the wedge spool member of the wedge spool control valve of the present invention.

FIG. 8 depicts and end view of the distal end of the wedge spool member of the wedge spool control valve of the present invention.

FIG. 9 depicts a detailed view of the highlighted area shown in FIG. 6.

FIG. 10 depicts a sectional view of the wedge spool control valve of the present invention along line 10-10 of FIG. 9.

FIGS. 11 through 14 depict sequential side sectional views of operation of the wedge spool control valve of the present invention.

FIG. 15 depicts a side sectional view of a double seal system for the cylinder rod assembly of the present invention.

FIG. 16 depicts a side sectional view of a double seal system and fluid drain mechanism for the cylinder rod assembly of the present invention.

FIG. 17 depicts a side view of the self-centering cylinder mounting assembly of the present invention.

FIG. 18 depicts a side sectional view of a cylindrical fluid reservoir of the present invention.

FIG. 19 depicts a side sectional view of a zero restriction check valve assembly of the present invention.

FIG. 20 depicts a side sectional view of an alternative embodiment of a zero restriction check valve assembly of the present invention.

FIG. 21 depicts a schematic view of one embodiment of a motor skid of the present invention having an electric regeneration system.

FIG. 22 depicts a schematic view of an alternative embodiment of a motor skid of the present invention not equipped with an electric regeneration system.

FIG. 23 depicts a schematic view of one embodiment of a motor skid of the present invention having an internal combustion engine.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, FIG. 1 depicts a front perspective view of support tower assembly 200 of hydraulic pumping apparatus 10 of the present invention. Elongate support tower assembly 200 is capable of being mounted to the upper end of a well that extends into the earth's crust. Said tower assembly 200 has substantially planar upper plate member 201 having optional central aperture 205, lower substantially planar plate member 202 having cut-out section 203 and elongate column support members 204 extending between said upper and lower plate members. Support tower assembly 200 provides a rigid support frame for supporting at least one hydraulic cylinder assembly 300. In the preferred embodiment, said elongate tower assembly 200 (and said at least one hydraulic cylinder assembly 300 supported therein) are mounted in substantially axial alignment over a well.

As depicted in FIG. 1, tandem cylinder assemblies 300 are mounted within support tower assembly 200. Each of said hydraulic cylinder assemblies 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301; because said hydraulic cylinder assemblies 300 are depicted in the retracted position in FIG. 1, piston rods 302 are not fully visible in FIG. 1. Cylinder barrels 301 are attached to upper plate member 201. In the embodiment depicted in FIG. 1, conventional bolted faster means 303 are used to connect said cylinder assemblies 300 to upper plate member 201; however, it is to be observed that pivot mounting assemblies depicted in FIG. 17 (described below) can be beneficially used for mounting said cylinder assemblies.

Spreader bar or bridle assembly 310 is connected to the distal end of each piston rod 302. Said bridle assembly 310 is attached to polished rod 320 using clamp member 321. Polished rod 320 is, in turn, connected to a length of interconnected sucker rods 322 that extends into a well (not shown in FIG. 1). Although not depicted in FIG. 1, it is to be understood that said sucker rods extend into said well, and connect to a down-hole pump situated at or near subterranean reservoir(s) from which fluid(s) are to be produced. Stop angle 312 and valve mounting plate 313 can also be mounted at desired locations within tower support tower assembly 200.

FIG. 2 depicts a front perspective view of support tower assembly 200 of hydraulic pumping apparatus 10 of the present invention including optional support base assembly 210. Said tower assembly 200 has substantially planar upper plate member 201 with optional central aperture 205, lower substantially planar plate member 202 having cut-out section 203 and elongate column support members 204 extending between said upper and lower plate members and providing structural support for tower assembly 200.

Tandem cylinder assemblies 300 are mounted within support tower assembly 200. Each of said hydraulic cylinder assemblies 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301. Cylinder barrels 301 are attached to upper plate member 201 with fasters 303, while the distal ends of piston rod members 302 are connected to bridle assembly 310.

Support base assembly 210 has a plurality of adjustable leg members 211. Each of said leg members 211 further has a substantially planar foot pad 212 to ensure stability of said support base assembly. Support base assembly 210 can be used to provide additional stability and support to tower assembly 200 when said tower assembly 200 is mounted on a well. In such instances, support base assembly 210 prevents all loading from being placed on a well equipped with hydraulic pumping apparatus 10, and instead transfers much of said loading (especially axial loading) to support base assembly 210. Although said support base assembly is depicted as having three leg members 211 (i.e., a tripod), it is to be observed that configurations having different numbers of leg members can also be used. Further, tie rods or other similar structural supports can be added as may be required.

FIG. 3 depicts a front view of hydraulic pumping apparatus of the present invention installed on a well 20 having wellhead 22 and flow lines 21. Tower assembly 200 has substantially planar upper plate member 201, lower substantially planar plate member 202 and elongate column support members 204 extending between said upper and lower plate members and providing structural support for tower assembly 200.

Tandem cylinder assemblies 300 are mounted within support tower assembly 200 in substantially parallel orientation. Each of said hydraulic cylinder assemblies 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301. As depicted in FIG. 3, cylinder barrels 301 are attached to upper plate member 201 with fasters 303, while the distal ends of piston rod members 302 are connected to bridle assembly 310. Bridle assembly 310 is attached to polished rod 320 using clamp member 321.

Polished rod 320 is movably disposed through dynamically sealing stuffing box 220 situated over well 20, and extends into wellhead 22 in a manner known to those having skill in the art. Although not shown in FIG. 3, polished rod 320 is connected to a length of interconnected sucker rods as described above which extend in said well to a down-hole reciprocating rod pump. Prime mover assembly 400 is connected to support tower assembly 200 via hydraulic hose 410.

As hydraulic cylinder assemblies 300 are actuated, bridle assembly 310 can be raised and lowered within tower assembly 200. Such raising and lowering of bridle assembly 310 imparts a reciprocating motion to polished rod 320 (and attached components) within well 20. Stuffing box 220 provides a dynamic seal against polished rod 320, causing pumped well fluids to exit said well via flow lines 21, rather than out the top of wellhead 22. Upper electrical switch 350 and lower electrical switch 340 are disposed within said tower assembly at predetermined locations.

FIG. 4 depicts a side view hydraulic pumping apparatus of the present invention installed on a well 20 having wellhead 22. Tower assembly 200 has substantially planar upper plate member 201, lower substantially planar plate member 202 and elongate column support members 204 extending between said upper and lower plate members and providing structural support for tower assembly 200. Cylinder assembly 300 is mounted within support tower assembly 200. Hydraulic cylinder assembly 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301. Upper switch 350 and lower switch 340 are disposed within said tower assembly at predetermined locations; in the preferred embodiment said switches 350 and 340 are electrical switches, although it is to be observed that other types of switches may be used.

Cylinder barrel 301 is attached to upper plate member 201 with fastener 303, while the distal end of piston rod member 302 is connected to bridle assembly 310. Bridle assembly 310 is attached to polished rod 320 using clamp member 321. Bridle assembly 310 has push plate 311 that extends outward from said bridle assembly 310. Polished rod 320 is movably disposed through dynamically sealing stuffing box 220 situated over well 20, and extends into wellhead 22 in a manner known to those having skill in the art. Hydraulic fluid supply line 410 provides a conduit for receiving hydraulic fluid from a hydraulic pump, such as included within a prime mover assembly (for example, prime mover assembly 400 depicted in FIG. 3).

FIG. 5 depicts a rear view of hydraulic pumping apparatus depicted in FIG. 4. Hydraulic fluid supply line 410 connects from a hydraulic pump or other source of hydraulic fluid to a controller assembly 100 having substantially vertical spool member 110 extending therefrom. Upper electrical switch 350 and lower electrical switch 340 are disposed within said tower assembly at predetermined locations.

As depicted in FIG. 5, push plate 311 of bridle assembly 310 is in contact with said spool member 110. Controller assembly outlet line 411 is a conduit (such as a hose, tube or the like) that connects controller assembly 100 to hydraulic junction assembly 412. Cylinder supply lines 413 extend from said hydraulic junction assembly 412 to hydraulic cylinder assemblies 300 in order to supply hydraulic fluid to said cylinder assemblies. Relief lines 414 also connect to cylinder assemblies 300 to provide for relief or bleeding of pressure from said cylinder assemblies.

FIG. 17 depicts a side view of a self-centering cylinder mounting assembly 330 of the present invention, which can be used to pivotally mount cylinder assemblies 300 to tower assembly 200 having upper plate member 201 and support columns 204 instead of fasteners 303 depicted in FIG. 1. Cylinder extension 331 extends through an aperture in upper plate member 201, and has downward facing partially-spherical member 333 having rounded lower surface and retention collar member 334. Rounded member 333 is movably disposed within generally concave bowl member 333. Said self-centering pivot mounting assembly 330 ensures that hydraulic cylinder assemblies 300 automatically find the center of gravity over a well (such as well 20 in FIG. 5) thereby preventing unwanted side loading on said cylinder assemblies 300.

FIG. 6 depicts a side sectional view of the wedge spool control valve assembly 100 of the present invention. Said wedge spool control valve assembly 100 can control the stroking of said hydraulic cylinder assemblies and, in turn, the reciprocation of sucker rods in and out of said well, and the function of the down-hole pump connected to said sucker rods, all as more fully described herein.

Wedge spool control valve assembly 100 comprises spool valve body 101 defining central flow bore 102 and bypass flow bore 103. In the preferred embodiment, central flow bore extension 104 extends below central flow bore 102. Upper flow channel 105 extends from said central flow bore 102 to bypass flow bore 103, while lower flow channel 106 extends from flow bore extension 104 to bypass flow bore 103. Check valve assembly 120 is disposed within bypass flow bore 103, and is beneficially positioned between upper flow channel 105 and lower flow channel 106.

Elongate spool member 110 having upper surface 110a is slidably received within bearings 107 which, in turn, are disposed within central flow bore 102. In this manner, elongate spool member is slidably received within said central flow bore 102 extending through spool valve body 101. It is to be observed that additional bearings 107 can be installed within central flow bore 102 to exceed the number of such bearings as shown in the figures.

In the preferred embodiment, elongate wedge spool member 110 extends through aligned apertures 113 in substantially parallel bottom plate member 111 and upper stroke stop member 112. Elongate spool member 110 has stroke stop collar 114 having increased diameter that is greater than the diameter of aperture 113 in upper stroke stop member 112; said stroke stop collar 114 limits upward movement of elongate spool member 110. The distance between upper stroke stop member 112 and spool valve body 101 (and, thus, the travel of elongate spool member 110) can be adjusted using stroke stop tie rods 115 and adjustment nuts 116.

FIG. 7 depicts a side view of the bottom portion of elongate wedge spool member 110 of the wedge spool control valve assembly 100 of the present invention, while FIG. 8 depicts an end view of bottom end 117 of said wedge spool member 110 of said wedge spool control valve assembly 100. Referring to FIG. 8, elongate wedge spool member 110 has a tapered bottom portion culminating in a substantially flat bottom surface 117. Still referring to FIG. 8, said tapered section is beneficially formed with flat surfaces 118 on opposing sides of said elongate spool member 110. Such configuration allows for improved bearing support through an entire cycle of said wedge spool control valve assembly 100, which in turn results in a much smoother function and increased life of said elongate spool member 110 and bearings 107. By contrast, a conventional conical spool member is not supported on its sides, thereby causing wear to be exerted on the spool valve body.

FIG. 9 depicts a detailed view of the highlighted area of wedge spool valve assembly 100 shown in FIG. 6. As more fully described below, pressure compensation occurs in this area because fluid under pressure surrounds said wedge spool member 110 evenly, thereby allowing free stroking (movement) of said wedge spool member 110 within central flow bore 102. FIG. 10 depicts a bottom sectional view of the wedge spool control valve 100 of the present invention along line 10-10 of FIG. 9. Elongate wedge spool member 110 having bottom surface 117 and opposing flat side surfaces 118 is disposed within bearings 107, which is in turn disposed within central flow bore 102 in valve body 101. It is to be observed that bottom surface can have a curved (convex) shape, if desired. Additionally, it is to be further observed that multiple additional bearings can also be provided in addition to the number shown in the drawings. Upper flow channel 105 is connected to said central flow bore 102.

FIGS. 11 through 14 depict sequential side sectional views of operation of the wedge spool control valve assembly 100 of the present invention. FIG. 11 depicts wedge spool control valve assembly 100 in the fully open position. As depicted in FIG. 12, wedge spool control valve assembly 100 is partially closed. FIG. 13 depicts wedge spool control valve assembly 100 closed even further, while FIG. 14 depicts said wedge spool control valve assembly 100 in the fully closed position.

A variable frequency drive (“VFD”), typically included as part of a prime mover assembly (such as the alternate embodiment skid packages described in FIGS. 21-23 hereof) and connected to a controller mechanism, can be used to gradually ramp an electric motor (driving a hydraulic pump) up to operating speed to lessen mechanical and electrical stress, thereby reducing maintenance and repair costs and extending the life of the motor and the drive equipment. Said VFD can be programmed to ramp up the motor much more gradually and smoothly, and can operate the motor at less than full speed to decrease wear and tear.

In operation, wedge spool control valve assembly 100 of the present invention controls the actuation of hydraulic cylinder assemblies and, thus, stroking of a down-hole pump. Reference is made to FIG. 14, depicting elongate spool member 110 in the downward, fully-closed position. With spool member 110 of the wedge spool control valve assembly 100 in the downward position, the lower electric switch (see, switch 340 in FIGS. 5 and 6) is triggered, signaling the VFD to gradually ramp up power to the electric motor, or soft start, which drives the hydraulic pump of the prime mover assembly.

Hydraulic fluid is pumped through a line from the hydraulic pump of the prime mover to the wedge spool control valve assembly 100. Hydraulic fluid enters said wedge spool control valve assembly 100 through bypass bore 103. Simultaneously, check valve assembly 120 opens, allowing fluid to continue flowing through bypass bore 103. Fluid flowing through bypass port 103 continues through line(s) or hose(s) (see, line 411 in FIGS. 4 and 5) connected to cylinder assemblies, thereby causing said cylinder assemblies to retract. As said cylinder assemblies retract, bridle assembly 310 will travel upward, removing downward force on wedge spool member 110.

Hydraulic fluid passes through lower flow channel 106 and bore extension 104, into central flow bore 102, forcing wedge spool member 110 in an upward direction. Said hydraulic cylinder assemblies continue to retract, until upper electric switch (see, switch 350 in FIGS. 4 and 5). Actuation of such switch signals the VFD to ramp down power to the electric motor which, in turn, winds down the hydraulic pump and the flow of fluid from said pump to said wedge spool control valve 100 and, ultimately, hydraulic cylinder assemblies.

With the pumping stopped and the hydraulic cylinder assemblies retracted a predetermined amount, the down stroke portion of the cycle commences. As the down stroke portion of the cycle commences, fluid is forced (by the weight of the rod string load) down through bypass bore 103. Check valve assembly 120 closes, thereby diverting hydraulic fluid through upper flow channel 105 and central flow bore 102, as well as bore extension 104 and lower flow channel 106. Said fluid then flows out of wedge spool control valve assembly, and through a conduit back to a hydraulic fluid reservoir in prime mover skid.

As the piston rods of said hydraulic cylinder assemblies extend, push plate 311 connected to bridle 310, contacts the upper surface of elongate spool member 110, driving it downward. Said elongate spool member 110 will gradually restrict the flow of fluid while simultaneously decreasing the rate of speed until the motion is almost stopped. The weight of the rod string acts on said wedge spool member 110 which, in turn, eliminates loading on the pump and motor.

If the pumping unit is not equipped with an electrical regeneration unit, the motor will be turned off until the down stroke cycle is complete. However, when an electrical regeneration unit is installed, the motor is switched into reverse until the down stroke cycle is complete.

The process repeats itself with bottom switch being actuated, thereby triggering the VFD to slowly ramp up the electric motor. In this position, most of the well load is exerted on the wedge spool. As a result, start up loading on the electric motor is reduced, thereby reducing electric consumption and shock on the entire system. From this position, the up stoke portion of the cycle begins, and the process is repeated.

The critical variable for operation of the wedge spool control valve of the present invention is distance (i.e., the stroke distance of hydraulic cylinders), rather than time as in with other conventional hydraulic pumping units. As such, the pumping apparatus of the present invention is not affected by the rate of speed on the down stroke cycle. When the push plate 311 (see FIGS. 4 and 5) comes in contact with wedge spool member 110, it ramps down the flow of fluid, then stops the down stroke in the same position, no matter the down-stroke speed. Other conventional units have multiple switches on the bottom of the stroke—one to slow the rate of down stroke speed, and the other to stop and start the up stroke cycle. Changing of the stroke speed requires readjustment of the switches, resulting in additional costs and potential problems that are not a concern with the present invention

During normal operating functions, when wedge spool member 110 reaches around (adjustable) the 98% closed position within bore 102 and bore extension 104, push plate 311 has triggered the VFD to start the up stroke cycle. In the event of a power failure, or if the unit shuts down for any reason, the spool valve will continue down until the piston rods of the hydraulic cylinder assemblies come in contact with rod end caps of said cylinder assemblies, which in turn bleeds hydraulic pressure from the entire system. This function adds a significant safety feature to the hydraulic pump apparatus of the present invention while also reduces the likelihood of fluid leaks.

The hydraulic pumping assembly of the present invention can be adjusted to speeds to as little as 1 stroke per hour. On the down stroke cycle, electricity supply is turned off. The present invention virtually eliminates parted rods caused by stuck pump or rod string due to the constant monitoring of incoming electric power supply and instantaneous shutdown on low voltage. The present invention constantly monitors down hole conditions, and promptly shuts down if an overload occurs thereby greatly reducing tubing and rod wear. The present invention further adjusts to the well feed in rate thereby eliminating the need for a timer. The present invention will automatically restart when the power supply returns to normal. The rod clamp is adjustable as with conventional units,

Both the up and down stroke speeds can be independently adjusted by the simple turning of a knob or valve which provides for infinite variable speed control. An optional clean electrical power regeneration package can be provided. The present invention is specifically designed to be well tender friendly and simple to operate; as a result, limited computer skills are required for operation of said invention

FIG. 15 depicts a side sectional view of a double seal system of the present invention, while FIG. 16 depicts a side sectional view of a double seal system and fluid drain mechanism for a hydraulic cylinder assembly of the present invention. Other conventional hydraulic rod pumping tanks and valve spools typically have only a single hydraulic cylinder rod seal and rod wiper system. With only a small amount of use, seals invariably start to wear. Due to high fluid pressure that such seals are subjected to, fluid often leaks past such seals and into the surrounding environment, causing unsafe conditions and/or environmental contamination.

The double sealing assembly 150 of the present invention eliminates problems associated with such conventional assemblies. The double sealing assembly of the present invention can be utilized in connection with hydraulic cylinder assemblies, and also with the wedge spool control valve of the present invention. Referring to FIG. 15, rod 160 is disposed through the double sealing assembly 150 of the present invention having rod wiper 151. Most conventional systems have only a single rod seal. Double sealing assembly 150 of the present invention has outer rod seal 152 and chamber 153 that acts to trap any contaminants that may pass the rod wiper and outer seal.

Chamber drain channel 154 extends from said chamber 153 to a waste container (not pictured); in the preferred embodiment, said waste container is maintained at ambient (typically atmospheric) pressure which in turn lets contaminants flush out of said drain channel 154 and into said waste container (instead of, as with conventional systems, leaking past the outer rod seals). As a result, internal high pressure seal 155 is kept free of most contaminants which in turn prevents contaminants from migrating inside. This, in turn, greatly increases the life of the cylinder or valve spool and also the time between servicing. The double sealing assembly 150 of the present invention allows operations to continue much longer, even with the main seal worn because the fluid is captured instead of leaking onto the surroundings. The double seal system of the present invention lasts many times longer than standard systems.

It is to be observed that double sealing assembly 150 of the present invention can also be utilized in connection with a wedge spool control valve of the present invention. Specifically, said double sealing assembly can be utilized in connection with seals associated with tapered wedge spool member 110, thereby increasing the life of such seals and, accordingly, the operating life of wedge spool control valve of the present invention.

FIG. 16 depicts a side sectional view of a double seal system and fluid drain mechanism for a hydraulic cylinder assembly 300 of the present invention having outer rod seal 171. Chamber drain channel 175 extends from said chamber 174, having upper seals 173 and lower seals 172, to a collection container (not pictured) via drain line 176. In the preferred embodiment, said collection container is maintained at ambient (typically atmospheric) pressure which in turn lets fluid flush out of said drain channel 175 and into said collection container (instead of, as with conventional systems, leaking into the surrounding environment).

FIG. 18 depicts a side sectional view of a cylindrical aluminum fluid reservoir 50 of the present invention. In the preferred embodiment, said cylindrical aluminum fluid tank 50 of the present invention has removable clamp-on bottom 51, bottom drain fitting 52, removable clamp-on top 53, fluid inlet 54, tower cylinder air line fitting 55, desiccant 56, cylindrical aluminum tank body 57, low fluid shut down switch 58, outlet fitting 59, closing ring clamp 60, gasket 61 and internal baffles 62. Fluid tank 50 is very easy to clean, will not rust, dissipates heat much more efficiently than conventional tanks. Hydraulic fluid remains clean and cool, thereby lasting much longer than in conventional reservoirs. In the preferred embodiment, said desiccant has a 1/16″ bleed hole, thereby permitting a very small amount of air change during the up and down cycles. This keeps a tremendous amount of moisture and contaminants out of the system, resulting in the fluid and components lasting much longer than conventional units.

FIG. 19 depicts a side sectional view of a zero restriction check valve assembly 80 of the present invention which can be used in connection with the hydraulic pump included within the prime mover assembly of the present invention. On the up stroke cycle, the motor and pump draw fluid from a fluid reservoir, through inlet port 81 which opens ball 82 to allow fluid to flow freely through port 83 and to a pump. This action also closes the ball 84 to the valve seat that to leads to a fluid return tank 85.

On the down stroke cycle, the regeneration unit and the VFD are programmed to reverse the electric motor to 0 cycles. The weight of the well string forces hydraulic fluid back through the pump, turning the motor in reverse and generating electricity which, in turn, goes back into the electrical grid. As fluid flows through port 83, fluid pressure will close ball 82 and open ball 84, which allows fluid to pass through a cooler and/or filter (not shown on FIG. 19) and, ultimately, into a fluid tank.

FIG. 20 depicts a side sectional view of an embodiment of a zero restriction check valve assembly 70 of the present invention. Said zero restriction check valve has valve body 71, fitting 72 (typically, SAE, JIC, NPTF, or other); ball 73 (which can be beneficially constructed of plastic), plug with stop pin 74 and curved seating surfaces 75. The zero restriction check valve assembly 70 has no springs, sharp corners or other surfaces/restrictions to impede fluid flow. The design reduced eddies in flow patterns causing cavitation and pump-damaging gas bubbles. Ball 73 moves easily within said valve.

FIG. 21 depicts a schematic view of one embodiment of a prime mover/motor skid 380 of the present invention having an electrical regeneration system. VFD 381 controls power to a motor and is controlled by a 2-switch mechanism. Said VFD 381 can be programmed to shut down when the following happens: high fluid temperature, low fluid level (leak), low incoming voltage with auto restart when power returns to normal, high hydraulic pressure caused by stuck rods, and/or down stream problems (frozen lines, closed valve or other). Said VFD can be programmed to operate at double the cycles (RPM) of the motor design with no adverse effects. In the preferred embodiment, said VFD has a potentiometer that controls the up stroke speed from 0 to 200% of motor rated speed.

Referring to FIG. 21, said motor skid 380 further includes the following:

381—Electrical regenerative mounted with VFD. On the down stroke cycle, the flow control 387 (below) is used as a back up so the down speed is controlled in the event that the unit fails. Fluid is forced through the pump; turning it in reverse so the pump now acts as a hydraulic motor that in turn drives the electric motor in reverse thereby sending electrical current back into the electrical grid. Fluid is diverted by zero restriction check valve assembly (396), also shown in detail in FIG. 19.

382—Electric motor

383—Hydraulic pump

384—Check valve to keeps the pump and motor from turning in reverse.

385—Hydraulic line to the tower

386—Control wire from the tower to the VFD

387—Flow control valve. Controls the down stroke speed from max.

389—Cooler

390—Filter

391—Reservoir

392—Desiccant

393—Air line to the top of the cylinders

394—Base (tank)

395—Base drain

396—Zero Restriction Check Valve and Electrical Regeneration (See, FIG. 19).

FIG. 22 depicts a schematic view of an alternative embodiment of a prime mover/motor skid 360 of the present invention having a non-electrical regeneration system. VFD 361 controls power to a motor and is controlled by a 2-switch mechanism. Said VFD can be programmed to shut down when the following happens: high fluid temperature, low fluid level (leak), low incoming voltage with auto restart when power returns to normal, high hydraulic pressure caused by stuck rods, and/or down stream problems (frozen lines, closed valve or other). Said VFD can be programmed to operate at double the cycles (RPM) of the motor design with no adverse effects. In the preferred embodiment, said VFD has a potentiometer that controls the up stroke speed from 0 to 200% of motor rated speed.

Referring to FIG. 22, said motor skid 360 further includes the following:

362—Electric motor

363—Hydraulic pump

364—Check valve to prevent the pump and motor from turning in reverse

365—Hydraulic line to the tower.

366—Control wire from the tower to VFD

367—Flow control valve to control the down stroke speed from max. to stop.

368—Electric valve. Said electric valve opens on the down stroke so fluid from the cylinders feeds back into the reservoir and closes on the up stroke so fluid from the pump retracts the cylinders.

369—Cooler

370—Filter

371—Reservoir

372—Desiccant

373—Air line to the top of the cylinders

374—Base (tank)

375—Base drain

FIG. 23 depicts a schematic view of one embodiment of a prime mover/motor skid assembly 270 of the present invention having an internal combustion engine. At the start of the up stroke cycle, the bottom tower switch (340 in FIG. 4) is actuated at the down stroke of cylinder assemblies 300.

Actuation of said switch ramps up the engine governor. Simultaneously, valves 278 and 286 slowly close, controlled by a timer mechanism that eliminates any shock on the up start. The up speed is controlled by predetermined setting of the governor. When the stroke gets close to the top, a switch (350 in FIG. 4) actuates controls that act to ramp the governor down to idle and simultaneously slowly opens valves 278 and 286. The down speed is controlled by the flow control valve 287. Valve 287 is also used as a brake that can lock the stroke in any location desired for tending to or performing work on a well.

Now continuing the down stroke, as in above, the down stroke continues until the wedge spool control valve 110 ramps down the speed and the down stroke length is reached. Hydraulic pressure can still be maintained as to prevent a sudden shock of pressure at the start of the up cycle. On the down stroke cycle, check valve 274 keeps pressure off valve 278 and pump 273. Valve 277 is depicted as a redundant check valve that isolates any back pressure on the pump. Valve 278 beneficially allows the engine to idle free of any pressure.

Electric valves 278 and 286 are normally open. In case of engine failure, on either the up or down stroke, at any position, the stroke will automatically go down, such that the spool push plate 311 comes contacts wedge spool 110, thereby gently ramping down the speed. The process continues until the end of the wedge spool valve's stroke is reached and all the hydraulic pressure is bled from the system, with hydraulic cylinders fully extended down. This process eliminates any danger of accidently causing injury from high hydraulic pressure.

Referring to FIG. 23, said motor skid 270 further includes the following components:

271—Enclosure for engine governor, timer, relays and valve controls

272—Internal Combustion engine

273—Hydraulic pump

274—Check valve

275—Hydraulic line to the tower

276—Control wire from the tower to the VFD

277—Check valve

278—Hydraulic fluid and pressure unloading valve

279—Cooler

280—Filter

281—Reservoir

282—Desiccant

283—Air line to the top of the cylinders

284—Base (tank)

285—Base drain

286—Downstoke cycle return valve

287—Flow control valve

In addition to the embodiments depicted in FIGS. 21 through 23, it is to be observed that an optional controller system can also be employed to control function of the various components of the present invention including, without limitation, components of prime mover/motor skid packages discussed herein. Said controller system can include a central processor for collecting data from sensors and sending signals to certain components to control operation of said components. In some applications, certain communication functions of the components of the present invention can be accomplished through the use of wireless communication and associated automation.

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

1. A reciprocating pumping apparatus for pumping fluids from a well comprising: a. a support frame mounted to said well; b. at least one hydraulic cylinder assembly mounted within said support frame in substantially axial alignment with said well; c. a hydraulic pump for supplying hydraulic fluid to said at least one hydraulic cylinder assembly; d. a wedge spool control valve disposed between said hydraulic pump and said at least one hydraulic cylinder assembly, e. an upper switch disposed in said support frame, wherein said upper switch stops pumping by said hydraulic pump when said at least one cylinder assembly is retracted a predetermined distance; and f. a lower switch disposed in said support frame, wherein said lower switch commences pumping by said hydraulic pump when said at least one cylinder assembly is extended a predetermined distance. 